Nanosilica dispersion well treatment fluid

ABSTRACT

A well treatment fluid is provided having an acidic nanosilica dispersion. The nanosilica dispersion of well treatment fluid may form a gelled solid after interaction with a formation over a period. Methods of reducing water production using the well treatment fluids are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.62/454,253 filed Feb. 3, 2017, and titled “NANOSILICA DISPERSION LOSTCIRCULATION MATERIAL (LCM) AND WELL TREATMENT FLUID.” For purposes ofUnited States patent practice, this application incorporates thecontents of the Provisional Application by reference in its entirety.

BACKGROUND Field of the Disclosure

The present disclosure generally relates to controlling lost circulationin a well during drilling with a drilling fluid and reducing waterproduction during production from the well. More specifically,embodiments of the disclosure relate to lost circulation materials(LCMs) and well treatment fluids.

Description of the Related Art

Various challenges are encountered during drilling and productionoperations of oil and gas wells. For example, fluids used in drilling,completion, or servicing of a wellbore can be lost to the subterraneanformation while circulating the fluids in the wellbore. In particular,the fluids may enter the subterranean formation via depleted zones,zones of relatively low pressure, lost circulation zones havingnaturally occurring fractures, weak zones having fracture gradientsexceeded by the hydrostatic pressure of the drilling fluid, and soforth. The extent of fluid losses to the formation may range from minorlosses (for example less than 10 barrels/hour ((bbl/hr), also referredto as seepage loss, to severe (for example, greater than 100 bbl/hr), orhigher, also referred to referred to as complete fluid loss. As aresult, the service provided by such fluid is more difficult or costlyto achieve.

Such lost circulation can be encountered during any stage of operationsand occurs when drilling fluid (or drilling mud) pumped into a wellreturns partially or does not return to the surface. While de minimisfluid loss is expected, excessive fluid loss is not desirable from asafety, an economical, or an environmental point of view. Lostcirculation is associated with problems with well control, boreholeinstability, pipe sticking, unsuccessful production tests, poorhydrocarbon production after well completion, and formation damage dueto plugging of pores and pore throats by mud particles. Lost circulationproblems may also contribute to non-productive time (NPT) for a drillingoperation. In extreme cases, lost circulation problems may forceabandonment of a well.

In another example, after a well is completed and becomes a producingwell, water production from the well may cause significant economicdrawbacks. High water production rates may cause a reduction in wellproductivity, an increase operating expenditures, and can completelyblock production from wells. Consequently, controlling and eliminatingunwanted water influx into oil or gas wells is a major concern ofproducers. The water produced in a well may be the result of awater-producing zone communicating with the oil or gas producing zone byfractures, high-permeability streaks, fissures, vugs, or the like. Waterproduction may also be caused by occurrences such as water coning, watercresting, bottom water, and channeling at the wellbore. Such waterproduction is typically produced at the expense of oil or gas recovery,and, in severe cases, the water influx may be so great that oil or gasproduction is choked off completely.

SUMMARY

Lost circulation materials (LCMs) are used to mitigate lost circulationby blocking the path of the drilling mud into the formation. The type ofLCM used in a lost circulation situation depends on the extent of lostcirculation and the type of formation. Lost circulation materials may beclassified into different categories, such as fibrous materials, flakymaterials, granular materials, gel type materials, crosslinkingpolymers, and loss control slurries. Such materials are frequently usedeither alone or in combination to control loss of circulation. The costsincurred in lost circulation situations may be due to lost time, lossesof drilling fluids, and losses of production. Existing LCMs may performpoorly in mitigation and prevention of moderate lost circulation andseepage type lost circulation, and may not be suitable for controllingsevere loss of circulation. Costs incurred in loss circulationsituations may be due to losses of drilling fluids, losses ofproduction, and the costs of LCMs.

In enhanced recovery techniques such as water flooding, an aqueous floodor displacement fluid is injected under pressure into an oil-containingsubterranean formation by way of one or more injection wells. The flowof the aqueous fluid through the formation displaces oil or gas anddrives it to one or more producing wells. However, the aqueousdisplacement fluid tends to flow through the most permeable zones in thesubterranean formation such that less permeable zones containing oil orgas are bypassed. This uneven flow of the aqueous displacement fluidthrough the formation reduces the overall yield of hydrocarbons from theformation. Enhanced recovery problems caused by permeability variationsin subterranean formations have been corrected by reducing thepermeability of the subterranean formation flow paths. The techniquesutilized to accomplish this reduction in the permeability of highpermeability zones are may be referred to as “conformance controltechniques.” Decreasing excess water production increases the productionwater/oil ratio (“WOR”), thus lowering water-handling cost. As oilproduction increases and water production decreases, conformance controltechniques can extend a well's economic life and increase return oninvestment (ROI). Existing techniques for controlling water productionin subterranean formations include the use of gelatin-forming polymers,concrete resin barriers, and hydrophilic polymers. However, existingtechniques may be unstable at high temperatures or in the presence ofcertain chemicals (for example, acids and brines), resulting indecomposition or degradation and reducing or eliminating theireffectiveness. Moreover, some polymers used for controlling waterproduction may be environmentally damaging.

In one embodiment, a method to reduce water production in a treatmentzone in a wellbore is provided that includes introducing a treatmentfluid into the wellbore such that the treatment fluid contacts thetreatment zone and reduces the water production in the treatment zone.The treatment fluid consists of a nanosilica dispersion. In someembodiments, the acidic nanosilica dispersion includes amorphous silicondioxide in the range of 5 weight percentage of the total weight (w/w %)to about 50 w/w %. In some embodiments, the acidic nanosilica dispersionincludes water in the range of 50 w/w % to 95 w/w %. In someembodiments, the treatment zone is located in a carbonate formation. Insome embodiments, the method includes maintaining the acidic nanosilicadispersion in contact with the treatment zone for a period, such thatthe acidic nanosilica dispersion forms a gelled solid. In someembodiments, the period is a range of 0.5 hours to 24 hours.

In another embodiment, a solid gelled material useful for reducing waterproduction is provided. The solid gelled material includes the reactionproduct of amorphous silicon dioxide and glycerin in water, such thatthe solid gelled material forms by introducing a nanosilica dispersionto a treatment zone. The acidic nanosilica dispersion includes amorphoussilicon dioxide in the range of 5 weight percentage of the total weight(w/w %) to about 50 w/w %, and water in the range of 50w/w % to 95 w/w%. In such embodiments, the acidic nanosilica dispersion contacts thetreatment zone having an elevated temperature for a period such that thesolid gelled material forms. In some embodiments, the acidic nanosilicadispersion has a pH that is acidic. In some embodiments, the treatmentzone is carbonate. In some embodiments, the acidic nanosilica dispersionhas a pH value that is reduced at introduction and a greater pH valueupon contact with the carbonate lost circulation zone.

In another embodiment, a method to reduce water production in atreatment zone in a wellbore is provided that includes introducing atreatment fluid into the wellbore such that the treatment fluid contactsthe treatment zone and reduces the water production in the treatmentzone. The treatment fluid consists of a nanosilica dispersion and atleast one of: calcium carbonate particles, fibers, mica, and graphite.In some embodiments, the fibers include at least one of: polyesterfibers, polypropylene fibers, starch fibers, polyketone fibers, ceramicfibers, glass fibers or nylon fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of a gelled solid formed by a mixture of ananosilica dispersion with added calcium carbonate in accordance with anembodiment of the disclosure;

FIG. 2 is a photograph of a gelled solid formed by a mixture of ananosilica dispersion with a monoethanolamine activator and addedcalcium carbonate in accordance with an embodiment of the disclosure;and

FIG. 3 is a photograph of a gelled solid formed by a mixture of ananosilica dispersion and a monoethanolamine activator in accordancewith an embodiment of the disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described more fully with referenceto the accompanying drawings, which illustrate embodiments of thedisclosure. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the illustratedembodiments. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art.

Embodiments of the disclosure include a nanosilica dispersion LCM forcarbonate formations to mitigate or prevent lost circulation in a well,as well as provide seepage control and minimize or prevent fluid loss.In some embodiments, the nanosilica dispersion may include amorphoussilicon dioxide in the range of about 5 weight percentage of the totalweight (w/w %) of the nanosilica dispersion to about 50 w/w %, glycerinin the range of about 3 w/w % to about 5 w/w %, and water in the rangeof about 50 w/w % to about 95 w/w %. It should be appreciated that othersuitable nanosilica dispersions may not include glycerin. In someembodiments, the nanosilica dispersion may be an acidic nanosilicadispersion and may have a pH of less than 7 before interaction with aformation. The nanosilica dispersion LCM may be introduced into a lostcirculation zone in a wellbore, such that the nanosilica dispersion LCMalters the lost circulation zone. The nanosilica dispersion LCM may beallowed to interact with the lost circulation zone for a period toenable the in-situ formation of a gelled solid as a result of theinteraction between the nanosilica dispersion and the carbonateformation.

Embodiments of the disclosure also include a nanosilica dispersion andan alkanolamine activator LCM to mitigate or prevent lost circulation ina well, as well as provide seepage control and minimize or prevent fluidloss. In some embodiments, the nanosilica dispersion may includeamorphous silicon dioxide in the range of about 5 w/w % to about 50 w/w%, glycerin in the range of about 3 w/w % to about 5 w/w %, and water inthe range of about 50 w/w % to about 95 w/w %. In some embodiments, thealkanolamine activator may be monoethanolamine. In some embodiments, thenanosilica dispersion may be an acidic nanosilica dispersion and mayhave a pH of less than 7 before interaction with the activator. Thenanosilica dispersion and alkanolamine activator LCM may be introducedinto a lost circulation zone in a wellbore, such that the nanosilicadispersion and alkanolamine activator LCM alters the lost circulationzone. The nanosilica dispersion and alkanolamine activator LCM may beallowed to interact with the lost circulation zone for a period toenable the in-situ formation of a gelled solid as a result of theinteraction between the nanosilica dispersion and the alkanolamineactivator.

Embodiments of the disclosure additionally include a nanosilicadispersion treatment fluid for carbonate formations to reduce or blockwater production such as, for example, a result of water floodingoperations for a producing well. In some embodiments, the nanosilicadispersion may include amorphous silicon dioxide in the range of about 5w/w % to about 50 w/w %, glycerin in the range of about 3 w/w % to about5 w/w %, and water in the range of about 50 w/w % to about 95 w/w %. Insome embodiments, the nanosilica dispersion may be an acidic nanosilicadispersion and may have a pH of less than 7 before interaction with aformation. In some embodiments, the nanosilica dispersion may beintroduced into a treatment zone of a well, such as by pumping through awellhead at a pump rate sufficient to position the well treatment fluidat the treatment zone. The treatment fluid may be allowed to interactwith the treatment zone for a period to enable the in-situ reactionbetween the nanosilica dispersion and the carbonate formation that formsthe gelled solid.

Embodiments of the disclosure further include a nanosilica dispersionand an alkanolamine activator treatment fluid to reduce or block waterproduction such as, for example, a result of water flooding operationsfor a producing well. In some embodiments, the nanosilica dispersion mayinclude amorphous silicon dioxide in the range of about 5 w/w % to about50 w/w %, glycerin in the range of about 3 w/w % to about 5 w/w %, andwater in the range of about 50 w/w % to about 95 w/w %. In someembodiments, the alkanolamine activator may be monoethanolamine. In someembodiments, the nanosilica dispersion may be an acidic nanosilicadispersion and may have a pH of less than 7 before interaction with theactivator. In some embodiments, the treatment fluid may be introducedinto a treatment zone of a well, such as by pumping through a wellheadat a pump rate sufficient to position the treatment fluid at thetreatment zone. The treatment fluid may be allowed to interact with thetreatment zone for a period to enable the in-situ formation of a gelledsolid as a result of the interaction between the nanosilica dispersionand the alkanolamine activator.

Nanosilica Dispersion LCM

In some embodiments, an LCM for a carbonate formation includes ananosilica dispersion. In some embodiments, the nanosilica dispersionmay include amorphous silicon dioxide in the range of about 5 w/w % toabout 50 w/w %, glycerin in the range of about 3 w/w % to about 5 w/w %,and water in the range of about 50 w/w % to about 95 w/w %. In someembodiments, the nanosilica dispersion may be an acidic nanosilicadispersion and may have a pH of less than 7 before interaction with aformation. In some embodiments, the nanosilica dispersion includes astabilizer of acetic acid. In some embodiments, the nanosilicadispersion has a pH in the range of 2 to 4 at 25° C., a specific gravityof 1.21 (g/ml) a viscosity of less than 30 cP at 25° C. In someembodiments, the nanosilica dispersion may be obtained from EvonikCorporation of Parsippany, N.J., USA.

In some embodiments, the nanosilica dispersion LCM may includeadditional materials. For example, in some embodiment the nanosilicadispersion LCM may include calcium carbonate particles, fibers (such aspolyester fibers, polypropylene fibers, starch fibers, polyketonefibers, ceramic fibers, glass fibers or nylon fibers), mica, graphite,or combinations thereof.

In some embodiments, the nanosilica dispersion and alkanolamineactivator LCM may be allowed to interact with the lost circulation zonefor a period. For example, the period may be of sufficient duration toenable formation of a gelled solid as a result of the interactionbetween the nanosilica dispersion and the alkanolamine activator. Theformed gelled solid may alter the lost circulation zone (for example, byentering and blocking porous and permeable paths, cracks, and fracturesin a formation in the lost circulation zone, such as forming a structurein a mouth or within a fracture). In some embodiments, the interactionperiod may be in the range of about 0.5 hours to about 24 hours.

As shown supra, the nanosilica dispersion may form a gelled solid whenin contact with calcium carbonate of a formation of a well. Uponintroduction of the nanosilica dispersion with the carbonate formation,the pH of the nanosilica dispersion may increase (due to reaction of anacid of the dispersion with the carbonate formation) and becomealkaline. Additionally, the delayed and controlled gelling of thenanosilica dispersion LCM may provide for easier pumping of the LCM. Thenanosilica dispersion LCM may be used at elevated temperatures in awellbore such as, for example, 100° F. or greater, such as 300° F.Moreover, the environmentally friendly properties of the nanosilicadispersion LCM may minimize or prevent any environmental impact andeffect on ecosystems, habitats, population, crops, and plants at orsurrounding the drilling site where the acidic nanosilica dispersion LCMis used.

Nanosilica Dispersion and Alkanolamine Activator LCM

In some embodiments, an LCM for a carbonate formation includes ananosilica dispersion and an alkanolamine activator. In someembodiments, the nanosilica dispersion may include amorphous silicondioxide in the range of about 5 w/w % to about 50 w/w %, glycerin in therange of about 3 w/w % to about 5 w/w %, and water in the range of about50 w/w % to about 95 w/w %. In some embodiments, the nanosilicadispersion includes a stabilizer of acetic acid. In some embodiments,the nanosilica dispersion may be an acidic nanosilica dispersion and mayhave a pH of less than 7 before interaction with the activator. In someembodiments, the nanosilica dispersion has a pH in the range of 2 to 4at 25° C., a specific gravity of 1.21 (g/ml) a viscosity of less than 30cP at 25° C. In some embodiments, the nanosilica dispersion may beobtained from Evonik Corporation of Parsippany, N.J., USA.

In some embodiments, the alkanolamine activator may includemonoethanolamine. In other embodiments, the alkanolamine activator mayinclude other alkanolamines, such as diethanolamine, triethanolamine,and their derivatives. In some embodiments, the volumetric ratio of thenanosilica dispersion to the alkanolamine activator is about 60:1.

In some embodiments, the nanosilica dispersion and alkanolamineactivator LCM may include additional materials. For example, in someembodiment the nanosilica dispersion and alkanolamine activator LCM mayinclude calcium carbonate particles, fibers (such as polyester fibers,polypropylene fibers, starch fibers, polyketone fibers, ceramic fibers,glass fibers or nylon fibers), mica, graphite, or combinations thereof.

In some embodiments, the nanosilica dispersion and alkanolamineactivator LCM may be allowed to interact with the lost circulation zonefor a period. For example, the period may be of sufficient duration toenable formation of a gelled solid as a result of the interactionbetween the nanosilica dispersion and the alkanolamine activator. Theformed gelled solid may alter the lost circulation zone (for example, byentering and blocking porous and permeable paths, cracks, and fracturesin a formation in the lost circulation zone, such as forming a structurein a mouth or within a fracture). In some embodiments, the formation ofthe gelled solid may include interaction with a carbonate formation inthe lost circulation zone.

In some embodiments, the period may be in the range of about 0.5 hoursto about 24 hours. In some embodiments, the period may be selected basedon the formation type of the treatment zone. For example, in someembodiments the interaction period for a carbonate formation may beabout 8 hours.

As shown supra, the nanosilica dispersion and alkanolamine activator mayform a gelled solid LCM after a sufficient period. The alkanolamineactivate may increase the rate of gelation of the nanosilica dispersionas compared to using the nanosilica dispersion alone as an LCM. In someembodiments, the gelling of the nanosilica dispersion may be controlledby varying the concentration of the alkanolamine activator, and thegelling may be controlled by changing the pH of the LCM. For example,increasing concentrations of the alkanolamine activator may increase thepH of the LCM and increase the rate of gelation of the LCM.Additionally, the alkanolamine activator exhibits no precipitation withthe nanosilica dispersion at elevated temperature, thus enabling use ofthe LCM composition as a single fluid pill (that is, without stagedmixing of each component). Consequently, the delayed and controlledgelling of the nanosilica dispersion LCM may provide for easier pumpingof the LCM. The nanosilica dispersion and alkanolamine activator LCM maybe used at elevated temperatures in a wellbore such as, for example,100° F. or greater, such as 300° F. Moreover, the environmentallyfriendly properties of the nanosilica dispersion and alkanolamineactivator LCM may minimize or prevent any environmental impact andeffect on ecosystems, habitats, population, crops, and plants at orsurrounding the drilling site where the nanosilica dispersion andalkanolamine activator LCM is used.

Nanosilica Dispersion Well Treatment Fluid

In some embodiments, a well treatment fluid for blocking excessive waterproduction in a producing well in a carbonate formation includes ananosilica dispersion. In some embodiments, the nanosilica dispersionmay include amorphous silicon dioxide in the range of about 5 w/w % toabout 50 w/w %, glycerin in the range of about 3 w/w % to about 5 w/w %,and water in the range of about 50 w/w % to about 95 w/w %. In someembodiments, the nanosilica dispersion includes a stabilizer of aceticacid. In some embodiments, the nanosilica dispersion may be an acidicnanosilica dispersion and may have a pH of less than 7 beforeinteraction with a formation. In some embodiments, the nanosilicadispersion has a pH in the range of 2 to 4 at 25° C., a specific gravityof 1.21 (g/ml) a viscosity of less than 30 cP at 25° C. In someembodiments, the nanosilica dispersion may be obtained from EvonikCorporation of Parsippany, N.J., USA.

In some embodiments, the nanosilica dispersion LCM may includeadditional materials. For example, in some embodiment the nanosilicadispersion LCM may include calcium carbonate particles, fibers (such aspolyester fibers, polypropylene fibers, starch fibers, polyketonefibers, ceramic fibers, glass fibers or nylon fibers), mica, graphite,or combinations thereof.

In some embodiments, the nanosilica dispersion treatment fluid may beintroduced into a treatment zone in a well, such as during a welltreatment operation. For example, the nanosilica dispersion treatmentfluid may be pumped through a wellhead at a pump rate sufficient toposition the well treatment fluid at the treatment zone. In someembodiments, the nanosilica dispersion treatment fluid may be introducedusing coiled tubing.

After introducing the nanosilica dispersion treatment fluid into thetreatment zone, nanosilica dispersion may be allowed to interact withthe treatment zone for a period. For example, the period may be ofsufficient duration to enable the in-situ formation of a gelled solid asa result of the interaction between the nanosilica dispersion and thecarbonate formation. The nanosilica dispersion treatment fluid may alterthe treatment zone to reduce or block water production by reducing thepermeability of flow paths in the formation (such as by forming a gelledsolid in or at the mouth of permeable paths). In some embodiments, theperiod may be in the range of about 0.5 hours to about 24 hours.

In other embodiments, the nanosilica dispersion treatment fluid may beused in producing wells or injection wells. For example, the treatmentzone may be a zone in a producing well. In some embodiments, thenanosilica dispersion treatment fluid may be used in combination withsecondary and tertiary flooding operations, such as water flooding. Forexample, the nanosilica dispersion treatment fluid may be used to reduceor block flow of water or other fluid during secondary and tertiaryflooding operations.

In some embodiments, the nanosilica dispersion treatment fluid may beused with one or more additional treatment fluids. For example, in someembodiments, an additional treatment fluid may be introduced into thetreatment zone after introduction of the nanosilica dispersion treatmentfluid and the elapse of the period for interaction between thenanosilica dispersion treatment fluid and the carbonate formation.

As shown supra, the nanosilica dispersion treatment fluid may form agelled solid when in contact with calcium carbonate of a formation of awell. Upon introduction of the nanosilica dispersion with the carbonateformation, the pH of the nanosilica dispersion may increase (due toreaction of an acid of the dispersion with the carbonate formation) andbecome alkaline. Additionally, the delayed and controlled gelling of thenanosilica dispersion treatment fluid may provide for easier pumping ofthe treatment fluid and introduction into the treatment zone. Thenanosilica dispersion treatment fluid may be used at elevatedtemperatures in a wellbore such as, for example, 100° F. or greater,such as 300° F. Moreover, the environmentally friendly properties of thenanosilica dispersion treatment fluid may minimize or prevent anyenvironmental impact and effect on ecosystems, habitats, population,crops, and plants at or surrounding the production site where thenanosilica dispersion treatment fluid is used.

Nanosilica Dispersion and Alkanolamine Activator Well Treatment Fluid

In some embodiments, a well treatment fluid for blocking excessive waterproduction in a producing well includes a nanosilica dispersion and analkanolamine activator. In some embodiments, the nanosilica dispersionmay include amorphous silicon dioxide in the range of about 5 w/w % toabout 50 w/w %, glycerin in the range of about 3 w/w % to about 5 w/w %,and water in the range of about 50 w/w % to about 95 w/w %. In someembodiments, the nanosilica dispersion includes a stabilizer of aceticacid. In some embodiments, the nanosilica dispersion may be an acidicnanosilica dispersion and may have a pH of less than 7 beforeinteraction with the activator. In some embodiments, the nanosilicadispersion has a pH in the range of 2 to 4 at 25° C., a specific gravityof 1.21 (g/ml) a viscosity of less than 30 cP at 25° C. In someembodiments, the nanosilica dispersion may be obtained from EvonikCorporation of Parsippany, N.J., USA.

In some embodiments, the alkanolamine activator may includemonoethanolamine. In other embodiments, the alkanolamine activator mayinclude other alkanolamines, such as diethanolamine, triethanolamine,and their derivatives. In some embodiments, the volumetric ratio of thenanosilica dispersion to the alkanolamine activator is 60:1.

In some embodiments, the nanosilica dispersion and alkanolamineactivator may be mixed to form a treatment fluid before use in a well.The resulting treatment fluid may be introduced into a treatment zone ina well, such as during a well treatment operation. For example, thenanosilica dispersion and alkanolamine activator treatment fluid may bepumped through a wellhead at a pump rate sufficient to position the welltreatment fluid at the treatment zone. In some embodiments, thenanosilica dispersion and alkanolamine activator treatment fluid may beintroduced using coiled tubing. After introducing the nanosilicadispersion and alkanolamine activator treatment fluid into the treatmentzone, the nanosilica dispersion and the alkanolamine activator may beallowed to interact with the treatment zone for a period. For example,the period may be of sufficient duration to enable the in-situ formationof a gelled solid as a result of the interaction between the nanosilicadispersion and the alkanolamine activator. The nanosilica dispersion andalkanolamine activator treatment fluid may alter the treatment zone toreduce or block water production by reducing the permeability of flowpaths in the formation (such as by forming a gelled solid in or at themouth of permeable paths).

In some embodiments, the interaction period may be in the range of about0.5 hours to about 24 hours. In some embodiments, the period may beselected based on the formation type of the treatment zone. For example,in some embodiments the interaction period for a carbonate formation maybe about 8 hours.

In some embodiments, the treatment fluid may be prepared at a well site,such as by mixing the nanosilica dispersion and alkanolamine activatorto form the treatment fluid. The nanosilica dispersion and alkanolamineactivator treatment fluid may be used in producing wells or injectionwells. For example, the treatment zone may be a zone in a producingwell. In some embodiments, the nanosilica dispersion and alkanolamineactivator treatment fluid may be used in combination with secondary andtertiary flooding operations, such as water flooding. For example, thenanosilica dispersion treatment and alkanolamine activator fluid may beused to reduce or block flow of water or other fluid during secondaryand tertiary flooding operations.

In some embodiments, the acidic nanosilica and alkanolamine activatordispersion treatment fluid may be used with one or more additionaltreatment fluids. For example, in some embodiments, an additionaltreatment fluid may be introduced into the treatment zone afterintroduction of the nanosilica dispersion and alkanolamine activatortreatment fluid and the elapse of a period for interaction between thenanosilica dispersion and the alkanolamine activator of the treatmentfluid.

As shown supra, the nanosilica dispersion and alkanolamine activator mayform a gelled solid after a sufficient period. The alkanolamine activatemay increase the rate of gelation of the nanosilica dispersion ascompared to using the nanosilica dispersion alone as a well treatment.In some embodiments, the gelling of the nanosilica dispersion may becontroller by varying the concentration of the alkanolamine activator,and the gelling may be controlled by changing the pH of the treatmentfluid. For example, increasing concentrations of the alkanolamineactivator may increase the pH of the treatment fluid and increase therate of gelation of the treatment fluid. Additionally, the alkanolamineactivator exhibits no precipitation with the nanosilica dispersion atelevated temperature, thus enabling use of the treatment fluid as asingle fluid without staged mixing of each component. Consequently, thedelayed and controlled gelling of the nanosilica dispersion andalkanolamine activator treatment fluid may provide for easier pumping ofthe treatment fluid after mixing at the surface and before introductionto the treatment zone. The nanosilica dispersion and alkanolamineactivator treatment fluid may be used at elevated temperatures in awellbore such as, for example, 100° F. or greater, such as 300° F.Moreover, the environmentally friendly properties of the nanosilicadispersion and alkanolamine activator treatment fluid may minimize orprevent any environmental impact and effect on ecosystems, habitats,population, crops, and plants at or surrounding the drilling site wherethe nanosilica dispersion and alkanolamine activator treatment fluid isused.

EXAMPLES

The following examples are included to demonstrate embodiments of thedisclosure. It should be appreciated by those of skill in the art thatthe techniques and compositions disclosed in the example which followsrepresents techniques and compositions discovered to function well inthe practice of the disclosure, and thus can be considered to constitutemodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or a similar result without departing from the spirit and scope ofthe disclosure

The following non-limiting example of an acidic nanosilica dispersionwas tested in combination with calcium carbonate to simulate the contactof the nanosilica dispersion when pumped into a carbonate formation.

The acidic nanosilica dispersion used was IDISIL® LPH 35 manufactured byEvonik Corporation of Parsippany, N.J., USA. The properties of thenanosilica dispersion are described in Table 1:

TABLE 1 Properties of Nanosilica Dispersion Nanosilica dispersion pH @25° C. 2-4 Specific Gravity (grams/milliliter (g/ml)) 1.2 Viscosity @25° C. (cP) <30 Stabilizer Acetic Acid Visual Appearance White/Off WhiteFreezing Point  0° C. Boiling point 100° C. Relative Density 1.160-1.225

The acidic nanosilica dispersion was a milky liquid that was completelymiscible in water and had the same evaporation rate as water.

In a first experiment, 90 milliliters (ml) of the acidic nanosilicadispersion was added to an empty beaker. The initial pH of the acidicnanosilica dispersion was measured to be 3.6. Next, 20 grams (g) ofcalcium carbonate was added to the acidic nanosilica dispersion withconstant stirring. The calcium carbonate was in powder form having anaverage particle size of 50 microns. The resultant pH of the nanosilicadispersion after the addition of 20 g of calcium carbonate was measuredto be 6.5.

Next, the mixture of the nanosilica dispersion with the added calciumcarbonate was plated in a high temperature and high pressure (HTHP)aging cell. The cell was static aged for 16 hours at 300° F. to simulatedownhole conditions.

After 16 hours of static aging at 300° F., the mixture of the nanosilicadispersion with the added calcium carbonate was converted into gelledsolid. FIG. 1 is a photograph 100 of the gelled solid formed by themixture of the nanosilica dispersion with the added calcium carbonate.The formation of the gelled solid after static aging at the elevatedtemperature of 300 ° F. shows that the acidic nanosilica dispersion canbehave as an LCM when introduced into carbonate formations.

In a second experiment, 90 milliliters (ml) of the acidic nanosilicadispersion was added to an empty beaker. Next, 10 grams (g) of calciumcarbonate was added to the acidic nanosilica dispersion with constantstirring. Next, 0.5 ml of monoethanolamine was added to the mixture ofthe acidic nanosilica dispersion and calcium carbonate.

The mixture of the nanosilica dispersion with the added calciumcarbonate and monoethanolamine was placed in a high temperature and highpressure (HTHP) aging cell. The cell was static aged for 8 hours at 300°F. to simulate downhole conditions.

After 8 hours of static aging at 300° F., the mixture of the nanosilicadispersion with the added calcium carbonate and monoethanolamine wasconverted into a gelled solid. FIG. 2 is a photograph 200 of the gelledsolid formed by the mixture of the nanosilica dispersion with the addedcalcium carbonate and monoethanolamine. The formation of the gelledsolid after static aging at the elevated temperature of 300° F. showsthat the acidic nanosilica dispersion can behave as an LCM whenintroduced into carbonate formations and further shows that the additionof an alkanolamine activator (for example, monoethanolamine) hastens therate of formation of the gelled solid (that is, the addition ofmonoethanolamine reduces the period for formation of the gelled solid).

In a third experiment, 120 ml of the acidic nanosilica dispersion wasadded to an empty beaker. The initial pH of the acidic nanosilicadispersion was measured to be 3.6. Next, 2 ml of monoethanolamine wasadded to the acidic nanosilica dispersion with constant stirring. Theresultant pH of the nanosilica dispersion after the addition of 2 ml ofmonoethanolamine was measured to be 9.28.

The mixture of the nanosilica dispersion with monoethanolamine and wasplaced in a high temperature and high pressure (HTHP) aging cell. Thecell was placed in an oven and static aged for 16 hours at 300° F. tosimulate downhole conditions.

After 16 hours of static aging at 300° F., the mixture of the nanosilicadispersion with the added monoethanolamine was converted into a gelledsolid. FIG. 3 is a photograph 300 of the gelled solid formed by themixture of the nanosilica dispersion with the added monoethanolamine.The formation of the gelled solid after static aging at the elevatedtemperature of 300° F. shows that the acidic nanosilica dispersion canbe used as a treatment fluid to reduce or block excessive waterproduction during the production of oil or gas from a well.

Ranges may be expressed in the disclosure as from about one particularvalue, to about another particular value, or both. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value, to the other particular value, or both, along withall combinations within said range.

Further modifications and alternative embodiments of various aspects ofthe disclosure will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the embodiments described inthe disclosure. It is to be understood that the forms shown anddescribed in the disclosure are to be taken as examples of embodiments.Elements and materials may be substituted for those illustrated anddescribed in the disclosure, parts and processes may be reversed oromitted, and certain features may be utilized independently, all aswould be apparent to one skilled in the art after having the benefit ofthis description. Changes may be made in the elements described in thedisclosure without departing from the spirit and scope of the disclosureas described in the following claims. Headings used described in thedisclosure are for organizational purposes only and are not meant to beused to limit the scope of the description.

What is claimed is:
 1. A method to reduce water production in atreatment zone in carbonate formation, comprising: introducing atreatment fluid into the wellbore such that the treatment fluid contactsthe treatment zone and reduces the water production in the treatmentzone, wherein the treatment fluid consists of an acidic nanosilicadispersion.
 2. The method of claim 1, wherein the acidic nanosilicadispersion comprises amorphous silicon dioxide in the range of 5 weightpercentage of the total weight (w/w %) to about 50 w/w %.
 3. The methodof claim 2, wherein the acidic nanosilica dispersion comprises water inthe range of 50 w/w % to 95 w/w %.
 4. The method of claim 1, comprisingmaintaining the acidic nanosilica dispersion in contact with thetreatment zone for a period, such that the acidic nanosilica dispersionforms a gelled solid.
 5. The method of claim 4, wherein the periodcomprises a range of 0.5 hours to 24 hours.
 6. A solid gelled materialuseful for reducing water production, where the solid gelled materialforms by introducing an acidic nanosilica dispersion to a treatment zonein a carbonate formation, the acidic nanosilica dispersion comprising:amorphous silicon dioxide in the range of 5 weight percentage of thetotal weight (w/w %) to about 50 w/w %; and water in the range of 50 w/w% to 95 w/w %; such that the acidic nanosilica dispersion contacts thetreatment zone having an elevated temperature for a period such that thesolid gelled material forms.
 7. The solid gelled material of claim 6,wherein the acidic nanosilica dispersion has a pH that is acidic.
 8. Thesolid gelled material of claim 6, wherein the acidic nanosilicadispersion has a pH value that is reduced at introduction and a greaterpH value upon contact with the carbonate formation.
 9. A method toreduce water production in a treatment zone in carbonate formation,comprising: introducing a treatment fluid into the wellbore such thatthe treatment fluid contacts the treatment zone and reduces the waterproduction in the treatment zone, wherein the treatment fluid consistsof an acidic nanosilica dispersion and at least one of: calciumcarbonate particles, fibers, mica, and graphite.
 10. The method of claim9, wherein the fibers comprise at least one of: polyester fibers,polypropylene fibers, starch fibers, polyketone fibers, ceramic fibers,glass fibers or nylon fibers.